Hey guys. A few days ago I'm cruising along and my CE light comes on out of the blue. The engine feels fine, so I don't worry about it too much. I get home and reset it by pulling the battery (I always just reset things at least once, because 4 out of 5 problems on my car are just sensor glitches). It stays off for two days, then come back on when I start the car and gun it a little in the morning. I leave the door open to listen to the engine as I gun it, and it seems to sputter and cough ever so slightly in the lower (0-2800) rpm ranges. Not real bad, but noticeable to me. I can't really feel it while I'm driving, it's so slight, it's just a sound.

I don't have an easy way to get to a mechanic; I moved to a new area and thus far there's no one up here that can work on BMWs. I would have to drive 45 minutes just to get the code read, and I have to work. So in the mean time, I'm wondering what you guys think and if there's any self-tests I can do on this. It's not the catalytic converters; those were replaced last month. Spark plugs are only a few months old too. Coils looked fine when I had them out for the plugs. I'm personally thinking it's oxygen sensors, because I've got 93k on my car and never replaced them. Can those go bad gradually? Is there a test to see if that's the problem without taking the car in?

Thanks for your thoughts, everyone.

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Thanks Bear. Actually, earlier this year I took it to an Advance and they plugged their little reader in and it couldn't read my engine codes. I do have OBDII, they said, but apparently it was a little too special for their code reader. I guess I could try an Auto Zone.

Bad MAF...yes, I should have remembered that was a common problem. My mechanic also said a few months ago that it wouldn't be a bad idea to replace my fuel filter, but I doubt that has anything to do with this. Even so, I'm going to go look for a DIY guide for that. If anyone knows how, please help point me in the right direction. Thanks!

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There isnt any trick for reading the codes on a obd2 car unfortunately your gonna have to get to a place that has a scanner. Now that you have moved to an area that is far from any repair shops maybe it would be a good idea to pick up a cheap obd2 scan tool on ebay or something.

As far as why the check engine light is coming on we could all sit here and guess as to what is causing it but really that doesnt accomplish much. Try to get the fault read asap and let us know what it is then maybe somebody here can give you some useful advise. I hope that its not the aftermarket Cats that are causing the light to come on, I have seen that so many times.
Best of luck,

By the way, if its the MAF, mine went and I read to dip it in 1/2 & 1/2 solution of water and "Simple Green" . It cleaned it off {be careful not to bend the wire} and put it back in_ presto...it worked fine.

My guess is the MAF sensor.
Sometimes you can clean the sensor inside the black plastic piece but I've also heard it's real sensitive and you could damage it if you're not careful. I've heard people spraying some WD40 to clean it.
Most times, they just need to be replaced. I've replaced 2 total.

Also remove the plastic cover(s) on your engine and take a look and listen at your vacuum hoses. The symptoms you describe could maybe be caused by a vacuum hose leak, and it's cheap and easy to check it out for yourself. Sorry if I've duplicated advice with this...

I appreciate the suggestions, guys. I'm going to have some time to spend on my car this weekend (since the woman's out of town, hehe), so I'll check into these things and report back. Thanks!

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